1. Field of the Invention
The present invention relates to a transmission circuit for ultrasonic diagnosis and a method for transmitting an ultrasonic wave, and particularly relates to a transmission circuit for ultrasonic diagnosis with a plurality of channels and a method for a transmitting an ultrasonic wave by a plurality of channels.
2. Description of the Related Art
A transmission circuit for ultrasonic diagnosis with a plurality of channels is used for ultrasonic diagnosis of a human body, for example, in combination with an ultrasonic diagnosis device. A transmission circuit for ultrasonic diagnosis is made of one semiconductor device including a plurality of driving circuits and a plurality of preceding stage circuits each of which corresponds to each driving circuit, for example. In this case, one driving circuit and its preceding stage circuit are allocated to each channel, and the driving circuit makes and transmits a driving signal with a high voltage in accordance with a transmission signal pattern from the preceding stage circuit. The driving signal with the high voltage is transmitted to ultrasonic wave generating circuits corresponding to channels (for example, piezo electric elements), and each piezo electric element generates an ultrasonic wave in accordance with the driving signal. Accordingly, ultrasonic waves are generated in each channel.
In ultrasonic diagnosis, it is preferable that ultrasonic waves generated in each channel reach (converge) at a desired site (focus) at almost the same timings. Accordingly, it is possible to strengthen ultrasonic wave energy at the desired site to improve accuracy of diagnosis.
One technique to converge ultrasonic waves is disclosed in JP-6-335480-A, for example.